EP0262058B1 - Rotating devices having blades for dissolving alloy elements and for dispersing gas in a bath of aluminium - Google Patents

Rotating devices having blades for dissolving alloy elements and for dispersing gas in a bath of aluminium Download PDF

Info

Publication number
EP0262058B1
EP0262058B1 EP87420245A EP87420245A EP0262058B1 EP 0262058 B1 EP0262058 B1 EP 0262058B1 EP 87420245 A EP87420245 A EP 87420245A EP 87420245 A EP87420245 A EP 87420245A EP 0262058 B1 EP0262058 B1 EP 0262058B1
Authority
EP
European Patent Office
Prior art keywords
disc
blades
bath
gas
duct
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP87420245A
Other languages
German (de)
French (fr)
Other versions
EP0262058A1 (en
Inventor
Gérard Hudault
Pierre Netter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Rio Tinto France SAS
Original Assignee
Aluminium Pechiney SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Aluminium Pechiney SA filed Critical Aluminium Pechiney SA
Priority to AT87420245T priority Critical patent/ATE47535T1/en
Publication of EP0262058A1 publication Critical patent/EP0262058A1/en
Application granted granted Critical
Publication of EP0262058B1 publication Critical patent/EP0262058B1/en
Expired legal-status Critical Current

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/05—Refining by treating with gases, e.g. gas flushing also refining by means of a material generating gas in situ
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20—Mixing gases with liquids
    • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/233—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements
    • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B21/00—Obtaining aluminium
    • C22B21/06—Obtaining aluminium refining
    • C22B21/064—Obtaining aluminium refining using inert or reactive gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20—Mixing gases with liquids
    • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/233—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements
    • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
    • B01F23/23311—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements through a hollow stirrer axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00—Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20—Mixing gases with liquids
    • B01F23/23—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/233—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements
    • B01F23/2331—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements
    • B01F23/23314—Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids using driven stirrers with completely immersed stirring elements characterised by the introduction of the gas along the axis of the stirrer or along the stirrer elements through a hollow stirrer element
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/05—Stirrers
    • B01F27/11—Stirrers characterised by the configuration of the stirrers
    • B01F27/112—Stirrers characterised by the configuration of the stirrers with arms, paddles, vanes or blades
    • B01F27/1125—Stirrers characterised by the configuration of the stirrers with arms, paddles, vanes or blades with vanes or blades extending parallel or oblique to the stirrer axis
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01F—MIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F27/00—Mixers with rotary stirring devices in fixed receptacles; Kneaders
    • B01F27/80—Mixers with rotary stirring devices in fixed receptacles; Kneaders with stirrers rotating about a substantially vertical axis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention relates to a rotary device with blades for dissolving alloying elements and dispersing gas in an aluminum bath contained in a container.
  • alloys are generally obtained by incorporating these elements in solid form or solid particles in an aluminum bath and by dispersing them as best as possible using specific devices so that they dissolve as quickly as possible.
  • US Pat. No. 3,227,547 proposes a method in which a device is used which, according to FIG. 14, comprises a shaft pierced along its axis by a channel intended for the passage of a gas, one end of which is connected to a source of gas and a drive motor, the other end comprising a disc of the same axis as the shaft and which is provided on its side wall with blades slightly inclined relative to the vertical which elongate along the generatrices of a straight prism of parallelogrammatic section with an axis passing through the center of the disc, the ends of which result from the intersection of said prism with a cylinder of the same axis as that resting on the side walls of the disc and whose small faces are located in the planes of the upper and lower faces of the disc.
  • This disc is pierced in the center by an opening which puts the gas distributor channel in communication with the bath and provided on its underside with radial notches through which the gases flow towards openings placed on its side wall and located between the blades. It should be noted that, according to the direction of rotation of the disc, the blades have their front face downwards.
  • This means is a rotary device for dissolving alloying elements and dispersing gas in an aluminum bath originating in particular from a direct sample from an electrolysis tank contained in a container, such as a transport pocket, comprising a shaft pierced along its axis by a channel intended for the passage of gas, connected at one end to a gas source and to a drive motor and comprising at its second end intended to be immersed in the bath a disc with the same axis as the shaft, and which is provided on its lateral wall with blades which are elongated along the generatrices of a right prism of parallelogrammatic section with an axis passing through the center of the disc, the ends of which result from the intersection of said prism with a cylinder of the same axis as that resting on the side wall of the disc, and whose small faces (6) are located in the planes of the upper and lower faces of the disc, characterized in that the large blade faces form an alpha angle of at most 45 degrees with a plane perpendicular to the shaft (
  • FIG 1 there is a disc (3) rotating in the direction (9) provided with blades (4) which have a large face (5) and a small face (6). At the end of their axes are orifices (7) in connection with the channel (2) via the tubular passages (8).
  • Figure 2 the shaft (1) pierced by a channel (2) having at its lower part a disc (3) of height h provided with blades (4) of thickness e forming an angle a with the horizontal and of parallelogrammatic section constituted by the large faces (5) and the small faces (6) which are flush with the upper and lower planes of the disc.
  • the orifice (7) for the gas inlet.
  • the disc which plunges into the aluminum bath is driven by a motor, not shown, in the direction of the arrow and gas is admitted by a source not shown in the channel (2) while the elements of alloys escape from a hopper placed above the bath near the tree.
  • a motor not shown
  • gas is admitted by a source not shown in the channel (2) while the elements of alloys escape from a hopper placed above the bath near the tree.
  • the invention finds its application in particular in the rapid production of aluminum alloys with a low alkali content.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Mixers Of The Rotary Stirring Type (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
  • Agricultural Chemicals And Associated Chemicals (AREA)
  • Compounds Of Unknown Constitution (AREA)
  • Medicines Containing Plant Substances (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Abstract

The invention relates to an apparatus for dissolving alloy elements and dispersing gas in an aluminum bath comprising a vertical shaft (1) pierced along its axis by a duct (2) intended for passing the gas, connected in its upper part to a gas source and to a drive motor and comprising in its lower part which is immersed in the bath a disc (3) with the same axis as the shaft. It is characterized in that the disc is provided with blades (4) which extend along the generatrices of a right prism of parallelogrammatic section, have a rounded end, are inclined with respect to the horizontal at an angle of at most 45 degrees, have their faces between the two planes containing the upper and lower faces of the disc and are provided with axial orifices (7) connected to the duct (2) by a tubular passage (3). The apparatus permits the rapid production of alloys with a low proportion of alkaline elements therein, in particular in a transportation ladle.

Description

La présente invention est relative à un dispositif rotatif à pales de mise en solution d'éléments d'alliage et de dispersion de gaz dans un bain d'aluminium contenu dans un récipient.The present invention relates to a rotary device with blades for dissolving alloying elements and dispersing gas in an aluminum bath contained in a container.

L'homme de l'art sait que les produits fabriqués avec de l'aluminium pur ne possèdent généralement pas les caractéristiques mécaniques convenables à de nombreuses utilisations et que, pour les leur conférer il faut le plus souvent allier cet aluminium à d'autres éléments tels que le silicium, le magnésium, le fer, le mangenèse, etc...Those skilled in the art know that products made from pure aluminum generally do not have the mechanical characteristics suitable for many uses and that, to confer them, it is most often necessary to combine this aluminum with other elements. such as silicon, magnesium, iron, mangenese, etc ...

Ces alliages sont généralement obtenus en incorporant ces éléments sous forme massive ou de particules solides dans un bain d'aluminium et en les dispersant le mieux possible à l'aide de dispositifs particuliers de manière qu'ils se dissolvent le plus rapidement possible.These alloys are generally obtained by incorporating these elements in solid form or solid particles in an aluminum bath and by dispersing them as best as possible using specific devices so that they dissolve as quickly as possible.

Or, actuellement dans toutes les installations industrielles, ces éléments sont introduits dans les fours de fonderie, ce qui a pour inconvénient:

  • - de conduire dans certaines parties du four à la formation de zones d'accummulation et d'agglomération des particules dont la dissolution demande un temps relativement long;
  • - de nécessiter des dispositifs de brassage très lourds et très coûteux dans le cas de fours de grande capacité;
  • - de consommer beaucoup d'énergie.
However, currently in all industrial installations, these elements are introduced into foundry furnaces, which has the disadvantage:
  • - to lead in certain parts of the oven to the formation of accumulation and agglomeration zones of the particles, the dissolution of which requires a relatively long time;
  • - to require very heavy and very expensive stirring devices in the case of large capacity ovens;
  • - consume a lot of energy.

En outre, ces dispositifs ont uniquement pour fonction de disperser des solides dans un liquide.In addition, these devices only have the function of dispersing solids in a liquid.

Or, l'homme de l'art de la fonderie se trouve non seulement confronté à un problème de fabrication d'alliage, mais, également à celui de se débarrasser de certaines impuretés contenues dans le métal telles que les métaux alcalins et alcalino-terreux qui ont des effets nocifs sur l'alliage produit comme celui d'augmenter la vitesse d'oxydation du métal fondu ou de fragiliser à chaud les pièces qui en sont issues.However, those skilled in the foundry not only find themselves faced with an alloy manufacturing problem, but also with that of getting rid of certain impurities contained in the metal such as the alkali and alkaline earth metals. which have harmful effects on the alloy produced, such as increasing the rate of oxidation of the molten metal or weakening hot the parts which result therefrom.

Pour éliminer ces alcalins, on recourt généralement soit à un traitement par un flux contenant par exemple des fluorures alcalins, soit à un traitement par un gaz chloré. Dans ce dernier cas, pour que le traitement soit valable, il faut que l'on dispose de moyens de dispersion de gaz dans un métal liquide suffisamment efficaces. Certes, ici encore, l'homme de l'art n'est pas resté inactif et a mis au point des dis- perseurs de gaz qui conviennent. On peut citer en particulier celui décrit dans le brevet français n° 2 512067.To remove these alkalis, use is generally made either of a treatment with a flux containing, for example, alkaline fluorides, or of treatment with a chlorinated gas. In the latter case, for the treatment to be valid, it is necessary to have means for dispersing gas in a sufficiently effective liquid metal. It is true that here again the person skilled in the art has not remained inactive and has developed suitable gas dispersers. Mention may in particular be made of that described in French patent n ° 2 512067.

Mais, l'homme de l'art de la fonderie cherche également à débarasser les bains de métal fondu des gaz qu'ils contiennent. Ainsi, l'US-A 3 227 547 propose un procédé dans lequel on utilise un dispositif qui suivant la figure 14 comprend un arbre percé suivant son axe par un canal destiné au passage d'un gaz dont une extrémité est reliée à une source de gaz et à un moteur d'entraînement, l'autre extrémité comportant un disque de même axe que l'arbre et qui est muni sur sa paroi latérale de pales faiblement inclinées par rapport à la verticale qui s'allongent suivant les génératrices d'un prisme droit de section parallèlo- grammatique d'axe passant par le centre du disque, dont les extrémités résultant de l'intersection dudit prisme avec un cylindre de même axe que celui s'appuyant sur les parois latérales du disque et dont les petites faces sont situées dans les plans des faces supérieure et inférieure du disque. Ce disque est percé au centre par une ouverture qui met en communication le canal distributeur de gaz avec le bain et muni sur sa face inférieure d'échancrures radiales par lesquelles s'écoulent les gaz vers des ouvertures placées sur sa paroi latérale et situées entre les pales. Il est à noter qui suivant le sens de rotation du disque, les pales ont leur face avant dirigée vers le bas.However, the person skilled in the art of foundry also seeks to rid the molten metal baths of the gases which they contain. Thus, US Pat. No. 3,227,547 proposes a method in which a device is used which, according to FIG. 14, comprises a shaft pierced along its axis by a channel intended for the passage of a gas, one end of which is connected to a source of gas and a drive motor, the other end comprising a disc of the same axis as the shaft and which is provided on its side wall with blades slightly inclined relative to the vertical which elongate along the generatrices of a straight prism of parallelogrammatic section with an axis passing through the center of the disc, the ends of which result from the intersection of said prism with a cylinder of the same axis as that resting on the side walls of the disc and whose small faces are located in the planes of the upper and lower faces of the disc. This disc is pierced in the center by an opening which puts the gas distributor channel in communication with the bath and provided on its underside with radial notches through which the gases flow towards openings placed on its side wall and located between the blades. It should be noted that, according to the direction of rotation of the disc, the blades have their front face downwards.

Mais tous ces moyens spécifiques de la fonction pour laquelle ils ont été conçus c'est-à-dire d'assurer un bon échange liquide-gaz et ne peuvent généralement pas être utilisés comme dispositifs de mise en solution d'éléments d'alliages, de sorte que pour exercer les deux fonctions: dissolution de solides plus ou moins denses et dispersion de gaz dans un métal liquide, l'homme de l'art est obligé de faire appel à deux types de dispositifs et donc à deux stades de traitement, ce qui prolonge d'autant le temps nécessaire à leur application.But all of these specific means of the function for which they were designed, that is to say of ensuring a good liquid-gas exchange and cannot generally be used as devices for dissolving alloying elements, so that in order to exercise the two functions: dissolution of more or less dense solids and dispersion of gas in a liquid metal, a person skilled in the art is obliged to use two types of device and therefore two stages of treatment, which extends all the time necessary for their application.

C'est pourquoi la demanderesse a essayé de trouver un moyen qui permette d'assurer simultanément les deux fonctions suivant des conditions d'exploitation intéressantes.This is why the applicant has tried to find a means which makes it possible to simultaneously ensure the two functions under advantageous operating conditions.

Ce moyen est un dispositif rotatif de mise en solution d'éléments d'alliage et de dispersion de gaz dans un bain d'aluminium provenant notamment d'un prélèvement direct d'une cuve d'électrolyse contenu dans un récipient, tel qu'une poche de transport, comprenant un arbre percé suivant son axe par un canal destiné au passage du gaz, relié à une première extrémité à une source de gaz et à un moteur d'entraînement et comportant à sa deuxième extrémité destinée à être immergée dans le bain un disque de même axe que l'arbre, et qui est muni sur sa paroi latérale de pales qui s'allongent suivant les génératrices d'un prisme droit de section parallélogrammatique d'axe passant par le centre du disque, dont les extrémités résultent de l'intersection dudit prisme avec un cylindre de même axe que celui s'appuyant sur la paroi latérale du disque, et dont les petites faces (6) sont situées dans les plans des faces supérieure et inférieure du disque, caractérisé en ce que les grandes faces des pales forment un angle alpha d'au plus 45 degrés avec un plan perpendiculaire à l'arbre (I), que suivant le sens de rotation du disque, les grandes faces des pales situes du côté de ladite première extrémité du canal (2) se trouvent en amont des grandes faces situées du côté de ladite deuxième extrémité du canal (2) et que lesdites pales sont pourvues à leur extrémité d'au moins un orifice reliée au canal par un passage tubulaire.This means is a rotary device for dissolving alloying elements and dispersing gas in an aluminum bath originating in particular from a direct sample from an electrolysis tank contained in a container, such as a transport pocket, comprising a shaft pierced along its axis by a channel intended for the passage of gas, connected at one end to a gas source and to a drive motor and comprising at its second end intended to be immersed in the bath a disc with the same axis as the shaft, and which is provided on its lateral wall with blades which are elongated along the generatrices of a right prism of parallelogrammatic section with an axis passing through the center of the disc, the ends of which result from the intersection of said prism with a cylinder of the same axis as that resting on the side wall of the disc, and whose small faces (6) are located in the planes of the upper and lower faces of the disc, characterized in that the large blade faces form an alpha angle of at most 45 degrees with a plane perpendicular to the shaft (I), that in the direction of rotation of the disc, the large faces of the blades located on the side of said first end of the channel (2) are upstream of the large faces situated on the side of said second end of the channel (2) and that said blades are provided at their end with at least one orifice connected to the channel by a tubular passage.

Ainsi, la demanderesse s'est-elle inspirée du dispositif décrit dans l'US-A 3 227 547. Mais elle y a ajouté trois éléments nouveaux.Thus, the Applicant was inspired by the device described in US-A 3,227,547. But there are added three new elements.

En effet, il n'est pas facile de mélanger un liquide à la fois à des produits de faible masse volumique comme les gaz qui ont tendance à s'élever rapidement et à s'échapper à l'atmosphère et à des métaux qui au contraire tombent rapidement au fond du bain et s'agglomèrent en un monticule dont la dissolution complète peut s'avérer impossible en raison d'échanges liquide-solide pratiquement nuls.Indeed, it is not easy to mix a liquid at the same time with products of low density like gases which tend to rise quickly and to escape to the atmosphere and to metals which on the contrary quickly fall to the bottom of the bath and agglomerate into a mound whose complete dissolution may prove impossible due to practically zero liquid-solid exchanges.

C'est pourquoi la demanderesse a supplé aux lacunes du dispositif de l'art antérieur en matière de mélange de produits de masse volumique élevée en donnant aux pales un angle par rapport à l'horizontale relativement petit contrairement à l'autre conception dans laquelle les pales ont un angle beaucoup plus grand et présentent donc une surface d'attaque du bain beaucoup plus grande et par suite exigent pour leur mise en mouvement une quantité d'énergie plus élevée.This is why the applicant has made up for the shortcomings of the prior art device in terms of mixing products with high density by giving the blades an angle relative to the relatively small horizontal, unlike the other design in which the blades have a much larger angle and therefore have a much larger bath attack surface and consequently require for their movement a higher amount of energy.

De plus, l'inclinaison des pales a été inversée de manière à permettre aux éléments d'alliage d'acquérir un mouvement ascendant dans le bain.In addition, the inclination of the blades has been reversed so as to allow the alloying elements to acquire an upward movement in the bath.

Enfin, l'admission de gaz dans le bain a été réalisée à l'extrémité des pales, là où la vitesse périphérique est la plus grande et où le «cassage» des bulles et leur dispersion dans le bain s'effectue le mieux.Finally, the admission of gas into the bath was carried out at the end of the blades, where the peripheral speed is greatest and where the "breaking" of the bubbles and their dispersion in the bath is best carried out.

Un tel moyen permet de réaliser des conditions particulières de marche favorable au but recherché, à savoir:

  • - mise en mouvement du bain généralisée à toute la poche, ce qui permet d'augmenter la vitesse de dissolution des éléments d'alliage et d'assurer une meilleure diffusion du gaz pour éliminer les alcalins;
  • - brusques variations de vitesse des veines fluides qui provoquent un déplacement relatif des grains de métaux en suspension par rapport au liquide;
  • - l'absence de tourbillons en surface qui sont la source d'une oxydation du bain;
  • - une fine dissémination des bulles gazeuses qui empêche leur remontée trop rapide à la surface du bain;
  • - une vitesse de rotation relativement faible et en tout cas convenable pour éviter l'usure du rotor.
Such a means makes it possible to achieve particular conditions of market favorable to the desired goal, namely:
  • - setting in motion of the bath generalized to the whole pocket, which makes it possible to increase the speed of dissolution of the alloying elements and to ensure a better diffusion of the gas to remove the alkalis;
  • - sudden variations in speed of the fluid veins which cause a relative displacement of the grains of metals in suspension compared to the liquid;
  • - the absence of eddies on the surface which are the source of oxidation of the bath;
  • - a fine dissemination of the gas bubbles which prevents their too rapid rise to the surface of the bath;
  • - a relatively low speed of rotation and in any case suitable for avoiding wear of the rotor.

Avec un tel dispositif équipé de passages tubulaires radiaux de diamètre compris entre 2 et 5 mm alimentés en gaz inerte contenant quelques pourcents en volume de chlore sous une pression comprise entre 0,1 et 0,3 MPa, tournant à une vitesse comprise entre 100 et 350 tours/minute, un disque ayant un diamètre correspondant entre le et le 1/3 du diamètre du récipient et placé à une distance du fond du récipient comprise entre le 1/3 et le 1/4 de la hauteur du bain, on a obtenu une grande vitesse de dissolution des éléments d'alliages utilisés habituellement dans la métallurgie de l'aluminium ainsi qu'une bonne élimination des éléments alcalins tels que le sodium et le lithium.With such a device equipped with radial tubular passages with a diameter between 2 and 5 mm supplied with inert gas containing a few percent by volume of chlorine under a pressure between 0.1 and 0.3 MPa, rotating at a speed between 100 and 350 revolutions / minute, a disc having a corresponding diameter between the and 1/3 of the diameter of the container and placed at a distance from the bottom of the container between 1/3 and 1/4 of the height of the bath, we have obtained a high speed of dissolution of the alloying elements usually used in aluminum metallurgy as well as a good elimination of alkaline elements such as sodium and lithium.

On parvient cependant à un optimum des résultats quand, de préférence, certaines caractéristiques complémentaires sont utilisées dans la conception du disque. Ce sont :

  • - le nombre de pales compris entre 4 et 8,
  • - la longueur de l'axe de chaque pale voisine du rayon du disque,
  • - l'épaisseur e de chaque pale comprise entre le 1/4 et les 3/4 de la hauteur du disque,
  • - la largeur de chaque pale comprise entre le 1/5 et les 4/5 du diamètre du disque,
  • - un angle a compris entre 10 et 20 degrés,
  • - un sens de rotation du disque tel que dans ce sens les grandes faces inférieures des pales se trouvent en amont des faces supérieures,
  • - les orifices d'amenée de gaz au bain disposés aux extrémités des axes des pales,
  • - un rapport diamètre sur hauteur du disque compris entre 12 et 5.
However, optimum results are obtained when, preferably, certain complementary characteristics are used in the design of the disc. Those are :
  • - the number of blades between 4 and 8,
  • - the length of the axis of each blade close to the radius of the disc,
  • - the thickness e of each blade between 1/4 and 3/4 of the height of the disc,
  • - the width of each blade between 1/5 and 4/5 of the diameter of the disc,
  • - an angle a between 10 and 20 degrees,
  • a direction of rotation of the disc such that in this direction the large lower faces of the blades are located upstream of the upper faces,
  • - the gas supply orifices to the bath arranged at the ends of the axes of the blades,
  • - a diameter to height ratio of the disc between 12 and 5.

L'invention sera mieux comprise à l'aide des figures jointes qui représentent:

  • . Figure 1 : une vue de dessus du rotor.
  • . Figure 2 : une vue de côté du rotor.
The invention will be better understood using the attached figures which represent:
  • . Figure 1: a top view of the rotor.
  • . Figure 2: a side view of the rotor.

Sur la figure 1, on distingue un disque (3) tournant dans le sens (9) muni de pales (4) qui présentent une grande face (5) et une petite face (6). A l'extrémité de leurs axes se trouvent des orifices (7) en liaison avec le canal (2) par l'intermédiaire des passages tubulaires (8).In Figure 1, there is a disc (3) rotating in the direction (9) provided with blades (4) which have a large face (5) and a small face (6). At the end of their axes are orifices (7) in connection with the channel (2) via the tubular passages (8).

Sur la figure 2 sont représentés l'arbre (1) percé par un canal (2) comportant à sa partie inférieure un disque (3) de hauteur h muni de pales (4) d'épaisseur e formant un angle a avec l'horizontale et de section parallélogrammatique constituée par les grandes faces (5) et les petites faces (6) qui affleurent les plans supérieur et inférieur du disque. A l'extrémité de l'axe d'une des pales figure l'orifice (7) d'admission de gaz.In Figure 2 are shown the shaft (1) pierced by a channel (2) having at its lower part a disc (3) of height h provided with blades (4) of thickness e forming an angle a with the horizontal and of parallelogrammatic section constituted by the large faces (5) and the small faces (6) which are flush with the upper and lower planes of the disc. At the end of the axis of one of the blades is the orifice (7) for the gas inlet.

En fonctionnement, le disque qui plonge dans le bain d'aluminium est entraîné par un moteur, non représenté, dans le sens de la flèche et du gaz est admis par une source non représentée dans le canal (2) tandis que les éléments d'alliages s'échappent d'une trémie placée au-dessus du bain à proximité de l'arbre. Sous l'action conjuguée du brassage imposé par le profil et l'orientation particuliers des pales et de l'action du gaz distribué par l'extrémité des pales, il en résulte une mise en solution rapide des éléments d'alliage et une élimination des impuretés alcalines.In operation, the disc which plunges into the aluminum bath is driven by a motor, not shown, in the direction of the arrow and gas is admitted by a source not shown in the channel (2) while the elements of alloys escape from a hopper placed above the bath near the tree. Under the combined action of stirring imposed by the particular profile and orientation of the blades and the action of the gas distributed by the end of the blades, this results in a rapid dissolution of the alloying elements and an elimination of alkaline impurities.

L'invention peut être illustrée à l'aide des exemples d'application suivants :The invention can be illustrated using the following application examples:

On a procédé à plusieurs essais de dissolution d'éléments d'alliages et d'élimination simultanées d'alcalins dans des bains d'aluminium issus de cuves d'électrolyse et contenus dans des poches.Several tests were carried out on the dissolution of alloying elements and the simultaneous elimination of alkalis in aluminum baths from electrolytic cells and contained in bags.

Les conditions générales étaient les suivantes :

  • - poche sensiblement cylindrique de dimensions : hauteur 1,60m, diamètre 1,70 m
  • - hauteur du bain dans la poche comprise entre 1,05 m et 1,30 m
  • - dispositif suivant l'invention placé dans l'axe de la poche avec un disque de diamètre 0,70 m de hauteur 0,06 m muni de 6 pales inclinées à 16 degrés
  • - alimentation en éléments d'alliage par une trémie placée au-dessus du bain à 0,40 m de l'arbre. Les conditions particulières de l'essai et les résultats figurent dans le tableau ci-après :
    Figure imgb0001
    Figure imgb0002
The general conditions were as follows:
  • - substantially cylindrical pocket of dimensions: height 1.60 m, diameter 1.70 m
  • - height of the bath in the pocket between 1.05 m and 1.30 m
  • - device according to the invention placed in the axis of the pocket with a disc of diameter 0.70 m high 0.06 m provided with 6 blades inclined at 16 degrees
  • - supply of alloying elements by a hopper placed above the bath 0.40 m from the tree. The specific conditions of the test and the results are given in the table below:
    Figure imgb0001
    Figure imgb0002

On constate qu'en moins de 10 minutes, on obtient une dissolution quasi totale de la plupart des éléments d'addition classiques de l'aluminium et que simultanément la teneur en Na et en Li peut être abaissée en moins de 10 minutes au voisinage de 3 ppm.It can be seen that in less than 10 minutes, an almost complete dissolution of most of the conventional aluminum additives is obtained and that simultaneously the content of Na and of Li can be lowered in less than 10 minutes in the vicinity of 3 ppm.

L'invention trouve son application notamment dans l'élaboration rapide d'alliages d'aluminium à basse teneur en alcalins.The invention finds its application in particular in the rapid production of aluminum alloys with a low alkali content.

Claims (7)

1. A rotary blade-type apparatus for dissolving alloy elements and dispersing gas in an aluminium bath coming in particular from tapping an electrolysis tank, contained in a container such as a transportation ladle, comprising shaft (1) which is pierced along its axis by a duct (2) intended for the passage of the gas, connected at a first end to a source of gas and to a drive motor and comprising at its second end intended for being immersed in the bath a disc (3) with the same axis as the shaft and which is provided on its side wall with blades (4) which extend along the generatrices of a right prism of parallelogrammatic section with its axis passing through the centre of the disc, the ends of which result from the intersection of said prism with a cylinder of the same axis as that bearing against the side wall of the disc, the small faces (6) of the blades being disposed respectively in the planes of the upper and lower faces of the disc, characterised in that the large faces (5) of the blades are forming an angle a of at most 45 degrees to a plane perpendicular to the shaft (1), that following the direction of rotation of the disc the large faces of the blades disposed on the side of the said first end of the duct (2) are disposed upstream of the large faces of the blades disposed on the side of the said second end of the duct (2) and in that the said blades are provided with at least one orifice (7) connected to the duct (2) by a tubular passage (8).
2. Apparatus according to claim 1 characterised in that the number of blades is between 4 and 8.
3. Apparatus according to claim 1 characterised in that each blade has an axis of a length with is close to the radius of the disc.
4. Apparatus according to claim 1 characterised in that each blade is of a thickness e of between one quarter and three quarters of the height of the disc.
5. Apparatus according to claim 1 characterised in that each blade is of a width of between one fifth and four fifths of the diameter of the disc.
6. Apparatus according to claim 1 characterised in that a is between 10 and 20 degrees.
7. Apparatus according to claim 1 characterised in that the ratio of diameter to height of the disc is between 12 and 5.
EP87420245A 1986-09-22 1987-09-18 Rotating devices having blades for dissolving alloy elements and for dispersing gas in a bath of aluminium Expired EP0262058B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT87420245T ATE47535T1 (en) 1986-09-22 1987-09-18 BLADED ROTATING DEVICE FOR DISSOLVING ALLOY ELEMENTS AND DISPERSING GAS IN AN ALUMINUM BATH.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8613362 1986-09-22
FR8613362A FR2604099B1 (en) 1986-09-22 1986-09-22 ROTARY DEVICE WITH PELLETS FOR THE SOLUTION OF ALLOY ELEMENTS AND GAS DISPERSION IN AN ALUMINUM BATH

Publications (2)

Publication Number Publication Date
EP0262058A1 EP0262058A1 (en) 1988-03-30
EP0262058B1 true EP0262058B1 (en) 1989-10-25

Family

ID=9339239

Family Applications (1)

Application Number Title Priority Date Filing Date
EP87420245A Expired EP0262058B1 (en) 1986-09-22 1987-09-18 Rotating devices having blades for dissolving alloy elements and for dispersing gas in a bath of aluminium

Country Status (10)

Country Link
US (1) US4802656A (en)
EP (1) EP0262058B1 (en)
AT (1) ATE47535T1 (en)
AU (1) AU586401B2 (en)
DE (1) DE3760846D1 (en)
ES (1) ES2011643B3 (en)
FR (1) FR2604099B1 (en)
GR (1) GR3000197T3 (en)
NO (1) NO873935L (en)
NZ (1) NZ221847A (en)

Families Citing this family (55)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8804267D0 (en) * 1988-02-24 1988-03-23 Foseco Int Treating molten metal
US5085830A (en) * 1989-03-24 1992-02-04 Comalco Aluminum Limited Process for making aluminum-lithium alloys of high toughness
US5143357A (en) * 1990-11-19 1992-09-01 The Carborundum Company Melting metal particles and dispersing gas with vaned impeller
US5160693A (en) * 1991-09-26 1992-11-03 Eckert Charles E Impeller for treating molten metals
JP2544686Y2 (en) * 1991-11-25 1997-08-20 株式会社ニフコ Fastener for linear objects
US5308045A (en) * 1992-09-04 1994-05-03 Cooper Paul V Scrap melter impeller
US5397377A (en) * 1994-01-03 1995-03-14 Eckert; C. Edward Molten metal fluxing system
US5678807A (en) * 1995-06-13 1997-10-21 Cooper; Paul V. Rotary degasser
JP3520286B2 (en) * 1996-07-16 2004-04-19 ペシネー・ジャポン株式会社 Rotary gas diffusion equipment for molten metal processing
US5709834A (en) * 1996-09-11 1998-01-20 Lin; Yeun-Junn Device for removing gas and impurities from the molten aluminum
US5944496A (en) * 1996-12-03 1999-08-31 Cooper; Paul V. Molten metal pump with a flexible coupling and cement-free metal-transfer conduit connection
US5951243A (en) 1997-07-03 1999-09-14 Cooper; Paul V. Rotor bearing system for molten metal pumps
US6027685A (en) * 1997-10-15 2000-02-22 Cooper; Paul V. Flow-directing device for molten metal pump
US6093000A (en) 1998-08-11 2000-07-25 Cooper; Paul V Molten metal pump with monolithic rotor
US6199836B1 (en) 1998-11-24 2001-03-13 Blasch Precision Ceramics, Inc. Monolithic ceramic gas diffuser for injecting gas into a molten metal bath
US6303074B1 (en) 1999-05-14 2001-10-16 Paul V. Cooper Mixed flow rotor for molten metal pumping device
US6689310B1 (en) 2000-05-12 2004-02-10 Paul V. Cooper Molten metal degassing device and impellers therefor
US6723276B1 (en) 2000-08-28 2004-04-20 Paul V. Cooper Scrap melter and impeller
US20050013715A1 (en) * 2003-07-14 2005-01-20 Cooper Paul V. System for releasing gas into molten metal
US7507367B2 (en) * 2002-07-12 2009-03-24 Cooper Paul V Protective coatings for molten metal devices
US7402276B2 (en) * 2003-07-14 2008-07-22 Cooper Paul V Pump with rotating inlet
US20070253807A1 (en) 2006-04-28 2007-11-01 Cooper Paul V Gas-transfer foot
US7470392B2 (en) * 2003-07-14 2008-12-30 Cooper Paul V Molten metal pump components
US7731891B2 (en) * 2002-07-12 2010-06-08 Cooper Paul V Couplings for molten metal devices
US7906068B2 (en) * 2003-07-14 2011-03-15 Cooper Paul V Support post system for molten metal pump
US7556766B2 (en) * 2005-11-15 2009-07-07 Alcoa Inc. Controlled free vortex scrap ingester and molten metal pump
US8337746B2 (en) 2007-06-21 2012-12-25 Cooper Paul V Transferring molten metal from one structure to another
US9643247B2 (en) 2007-06-21 2017-05-09 Molten Metal Equipment Innovations, Llc Molten metal transfer and degassing system
US9205490B2 (en) 2007-06-21 2015-12-08 Molten Metal Equipment Innovations, Llc Transfer well system and method for making same
US9409232B2 (en) 2007-06-21 2016-08-09 Molten Metal Equipment Innovations, Llc Molten metal transfer vessel and method of construction
US8366993B2 (en) * 2007-06-21 2013-02-05 Cooper Paul V System and method for degassing molten metal
US8613884B2 (en) 2007-06-21 2013-12-24 Paul V. Cooper Launder transfer insert and system
US9410744B2 (en) 2010-05-12 2016-08-09 Molten Metal Equipment Innovations, Llc Vessel transfer insert and system
US9156087B2 (en) 2007-06-21 2015-10-13 Molten Metal Equipment Innovations, Llc Molten metal transfer system and rotor
US8524146B2 (en) 2009-08-07 2013-09-03 Paul V. Cooper Rotary degassers and components therefor
US8444911B2 (en) * 2009-08-07 2013-05-21 Paul V. Cooper Shaft and post tensioning device
US8535603B2 (en) 2009-08-07 2013-09-17 Paul V. Cooper Rotary degasser and rotor therefor
US10428821B2 (en) * 2009-08-07 2019-10-01 Molten Metal Equipment Innovations, Llc Quick submergence molten metal pump
US8449814B2 (en) * 2009-08-07 2013-05-28 Paul V. Cooper Systems and methods for melting scrap metal
US8714914B2 (en) 2009-09-08 2014-05-06 Paul V. Cooper Molten metal pump filter
US9108244B2 (en) * 2009-09-09 2015-08-18 Paul V. Cooper Immersion heater for molten metal
US9903383B2 (en) 2013-03-13 2018-02-27 Molten Metal Equipment Innovations, Llc Molten metal rotor with hardened top
US9011761B2 (en) 2013-03-14 2015-04-21 Paul V. Cooper Ladle with transfer conduit
US10052688B2 (en) 2013-03-15 2018-08-21 Molten Metal Equipment Innovations, Llc Transfer pump launder system
EP3049745B1 (en) 2013-09-27 2018-11-07 Rio Tinto Alcan International Limited Dual-function impeller for a rotary injector
USD742427S1 (en) 2013-09-27 2015-11-03 Rio Tinto Alcan International Limited Impeller for a rotary injector
US10138892B2 (en) 2014-07-02 2018-11-27 Molten Metal Equipment Innovations, Llc Rotor and rotor shaft for molten metal
US10947980B2 (en) 2015-02-02 2021-03-16 Molten Metal Equipment Innovations, Llc Molten metal rotor with hardened blade tips
CN105833785A (en) * 2015-03-20 2016-08-10 共慧冶金设备科技(苏州)有限公司 Spiral stirring device and application equipment thereof
US10267314B2 (en) 2016-01-13 2019-04-23 Molten Metal Equipment Innovations, Llc Tensioned support shaft and other molten metal devices
CN105668619B (en) * 2016-01-27 2017-05-24 柳州豪祥特科技有限公司 Method for preparing anhydrous stannic chloride
US11149747B2 (en) 2017-11-17 2021-10-19 Molten Metal Equipment Innovations, Llc Tensioned support post and other molten metal devices
FR3088432B1 (en) 2018-11-14 2020-12-11 Commissariat Energie Atomique DEVICE FOR CHARACTERIZING A LIQUID MATERIAL
US20200360990A1 (en) 2019-05-17 2020-11-19 Molten Metal Equipment Innovations, Llc Molten Metal Transfer System and Method
US11873845B2 (en) 2021-05-28 2024-01-16 Molten Metal Equipment Innovations, Llc Molten metal transfer device

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1583591A (en) * 1922-06-29 1926-05-04 William E Greenawalt Apparatus for treating liquids with gases
US1579355A (en) * 1923-06-11 1926-04-06 William E Greenawalt Apparatus for treating liquids with gases
US2609189A (en) * 1949-04-26 1952-09-02 Combined Metals Reduction Comp Machine for conditioning liquids with gases
US3227547A (en) * 1961-11-24 1966-01-04 Union Carbide Corp Degassing molten metals
NO142830C (en) * 1978-02-28 1980-10-29 Trondhjems Mek Verksted As DEVICE FOR DISTRIBUTING A GAS IN A FLUID MEDIUM
FR2512067B1 (en) * 1981-08-28 1986-02-07 Pechiney Aluminium ROTARY GAS DISPERSION DEVICE FOR THE TREATMENT OF A LIQUID METAL BATH

Also Published As

Publication number Publication date
FR2604099B1 (en) 1989-09-15
DE3760846D1 (en) 1989-11-30
NO873935L (en) 1988-03-23
GR3000197T3 (en) 1990-12-31
AU7869787A (en) 1988-03-24
NO873935D0 (en) 1987-09-21
AU586401B2 (en) 1989-07-06
NZ221847A (en) 1990-04-26
US4802656A (en) 1989-02-07
EP0262058A1 (en) 1988-03-30
ES2011643B3 (en) 1990-02-01
FR2604099A1 (en) 1988-03-25
ATE47535T1 (en) 1989-11-15

Similar Documents

Publication Publication Date Title
EP0262058B1 (en) Rotating devices having blades for dissolving alloy elements and for dispersing gas in a bath of aluminium
EP0073729B1 (en) Stirring equipment for the dispersion of gas during the treatment of metal baths
CA1165117A (en) Gas injection for the treatment of a molten metal bath
EP0170600B1 (en) Chloridizing ladle for aluminium alloys to remove magnesium
JP2010532427A (en) Rotary stirring device for processing molten metal
EP1332235B1 (en) Rotary gas dispersion device for treating a liquid metal bath
US6056803A (en) Injector for gas treatment of molten metals
NO328073B1 (en) Process for removing light metals from aluminum
CA2251230C (en) Rotary gas dispersion device for treating a liquid aluminium bath
FR2604107A1 (en) Rotary device for placing alloy elements in solution and for dispersing gas in a bath of aluminium
EP0419378B1 (en) Apparatus for treating a static aluminium bath of large surface area using gases
JP5318326B2 (en) Gas injection nozzle device and gas injection equipment provided with the same
JPH0790406A (en) Method for degassing molten aluminum and aluminum alloy and device therefor
WO2003095686A1 (en) Device for the in-line treatment of liquid metal by means of gas and filtration
WO1996016193A1 (en) Device for degassing and separating the inclusions in a liquid metal bath
JPH02115324A (en) Device for discharging and dispersing bubble into liquid
US20200182246A1 (en) Open exit molten metal gas injection pump
EP0223722A1 (en) Device and process for the low-pressure injection of pulverulent additives into a stream of molten metal
FR3135089A1 (en) Petroleum coke filling unit and filling process
FR2488283A1 (en) Leaching tower for poly:dispersed ores - esp. for leaching potassium chloride out of sylvinite, has coaxial cylinders of specified dimensions
JPH02115323A (en) Device for discharging and dispersing bubble into liquid
JPH07190639A (en) Molten metal treating device
FR2529230A1 (en) METHOD AND APPARATUS FOR DEGASSING METAL FUSION BATH AND / OR REMOVING NON-METALLIC IMPURITIES FROM THESE BATHS

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AT BE CH DE ES GB GR IT LI LU NL SE

17P Request for examination filed

Effective date: 19880414

17Q First examination report despatched

Effective date: 19890206

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): AT BE CH DE ES GB GR IT LI LU NL SE

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GR

Free format text: LAPSE BECAUSE OF FAILURE TO SUBMIT A TRANSLATION OF THE DESCRIPTION OR TO PAY THE FEE WITHIN THE PRESCRIBED TIME-LIMIT

Effective date: 19891025

REF Corresponds to:

Ref document number: 47535

Country of ref document: AT

Date of ref document: 19891115

Kind code of ref document: T

ITF It: translation for a ep patent filed

Owner name: ING. A. GIAMBROCONO & C. S.R.L.

GBT Gb: translation of ep patent filed (gb section 77(6)(a)/1977)
REF Corresponds to:

Ref document number: 3760846

Country of ref document: DE

Date of ref document: 19891130

REG Reference to a national code

Ref country code: GR

Ref legal event code: FG4A

Free format text: 3000197

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: AT

Effective date: 19900918

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: SE

Effective date: 19900919

Ref country code: ES

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19900919

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: LU

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 19900930

Ref country code: LI

Effective date: 19900930

Ref country code: CH

Effective date: 19900930

Ref country code: BE

Effective date: 19900930

26N No opposition filed
BERE Be: lapsed

Owner name: ALUMINIUM PECHINEY

Effective date: 19900930

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Effective date: 19910401

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee
REG Reference to a national code

Ref country code: CH

Ref legal event code: PL

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Effective date: 19910601

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Effective date: 19910918

GBPC Gb: european patent ceased through non-payment of renewal fee
REG Reference to a national code

Ref country code: GR

Ref legal event code: MM2A

Free format text: 3000197

EUG Se: european patent has lapsed

Ref document number: 87420245.0

Effective date: 19910527

REG Reference to a national code

Ref country code: ES

Ref legal event code: FD2A

Effective date: 19911011

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: IT

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES;WARNING: LAPSES OF ITALIAN PATENTS WITH EFFECTIVE DATE BEFORE 2007 MAY HAVE OCCURRED AT ANY TIME BEFORE 2007. THE CORRECT EFFECTIVE DATE MAY BE DIFFERENT FROM THE ONE RECORDED.

Effective date: 20050918